Vehicle lamp



Jan. l1, 1944. A. cHlTl VEHICLE LAM? Filed Mayu, 1940 Patented Jan. 11,1944 VEHICLE LAMP' Aroldo Chiti, Turin', Italy; vested in the AlienProperty Custodian ApplicationMay 14, 1940, Serial No. 335,177 lnltalyMay 22, 1939 1 Claim.

This invention relates; to lamps for` motor vehicles. and mechanizedtroop transports. An object of this invention is to provide a lampemitting, a light beam,` fromv whichl the passive rays4 issuing from thelamp. lament and the rays incorrectly. reflected.` by the reflectingsurface are eliminated by means of: screens arranged above and under thecausticformed by the, rays reiiected by the reflector and convergingtowards a focal point, in order to avoid formation of a halo around thelight beam issuing from the lamp, which, as is well known, is the maincause of glaring and reverberation produced by fog and impairing vision.

A further object of this invention is to provide a lamp of above typewith a reiiector of an ellipsoidal form and a source of lightsubstantially in a focus of said reflector so as to concentrate thelight beam in a caustic in the other focus, a pair of opaque blades, oneof which is arranged directly above the zone of said caustic while theother is arranged directly underneath said region for intercepting therays which do not pass through the geometrical focus of the reflector.The light is sent out in the form of a luminous fan-like blade limitedto its incidence path. This feature is of high importance in mechanisedtroop transports as it permits concealment thereof. In fact if thevehicles are looked at from a point above the lamp, no direct ray, orrays reflected by the ground, attains the observers eye. The section ofthe beam sent out through a double screen appears sharply and in arectangular form, which may be reduced to the form of a luminous blade;it is however also possible to obtain a beam of circular, triangular orother section to suit particular requirements.

Other details concerning the invention will appear from the followingspecification and reference to the annexed drawing which showsdiagrammatically and by Way of example some embodiments of theinvention.

Fig. 1 is a Vertical axial cross-sectional' view, partly in elevation,of a device embodying one form of my invention and showing a singlelight intercepting blade.

Fig. 2 is a diagrammatic cross-sectional View taken on the line II-II ofFig. 1 but showing a second light intercepting blade and a light filtertogether with means for supporting and adjusting the positions of thesecond blade and filter.

Fig. 3 shows a modied construction of the Vehicle lamp.

Fig. 4 shows a two-focal lens adapted for the arrangement according tothe invention.

(Cl. 24U-41.3),

l denotes a reflectingA device of half ellipsoid form having at itsfront part a cylindrical refiecting surface 2. The centre of thefilament of the lamp 3 is located in the focus F of the ellipsoidaldevice l. In the second focus F' of the ellipsoid comprising thereecting surface I converge all rays issuing from the central luminouspoint F of the lament of the lamp 3. The rays issuing from. theremainingparts of the lamp filament intersect at other points of the rerlectoraxis in front of or behind the focus F thuscreating a focal caustic.

According to the invention a screening blade 4 is placed underneath thefocal caustic and perpendicular thereto at an intermediate point of thecaustic, said blade intercepting all diverging and converging raysissuing from the filament in zones in front of or behind the main focalpoint F, intercepting also the passive rays due to defects ofconstruction of the reflecting unit, the blade letting on the contraryfree passage to all rays issuing from the geometric focus of theellipsoid. The blade 4 is adjustably mounted on a cover 6 by means ofscrews 4 engaged in slots in the blade (Fig. 2), so that screening maybe increased in order to limit the angle of aperture of theanti-dazzling beam of light thus sharply adjusting the angle ofoccultation until all upwardly directed rays are eliminated.

In order to obtain a double screening according to the invention,another screening blade 5 (Fig. 3) is located above the caustic, saidblade being movable through a remote control 5 (Fig. 2) The blades 4 and5 have a straight profile it being important generally to obtain a largehoriyzontal lighting eld; it is however obvious that that the prole ofthe blades may be so shaped as to obtain many diiferent forms of theissuingr beam of light. The cylindrical reilecting body 2 carriessecured at its front part the cover 6 carrying the screening blades 4and 5 and the correcting lens 1. By this simple arrangement a highlighting efliciency is obtained owing to the wide angular aperture ofthe lamp rays captured by the reflector and the enlarged angular lightedheld in the horizontal and downward direction produced by the reectionof the cylindrical mirror and by the lamp rays falling directly on thelens l. The unit is enclosed in a casing 8, as in ordinary vehiclelights, said casing being provided with a protecting glass 9 havinglinear Vertical lenticular elements for enlarging the beam of light inthe horizontal direction.

A further advantage ofthis arrangement is obtained through the apertureof emergence of the beam of light, which may be of very reduceddiameter, this advantage is of great importance when the light is usedfor mechanised troop transports, more particularly for tanks. For thesevehicles the double screening lamp type (blades 4 and 5) Will be moreconveniently used for preventing visibility from aircraft. A vehiclelamp adapted for this use is constituted by an optical unit such asdescribed, constituted by an ellipsoid and a two-focal very smalllens 1. The inner surface of the lens support should be darkened inorder to avoid any visible reection or diffusion. The optical featuresof this lamp permit of including in the lamp itself and in a small spacea coloured prismatic or lenticular lter I carried by an oscillating armI0' having a lever i" by means of which it can be remotely controlledduring drive, for instance a yellow cadmium sulphide glass lter toprevent eye fatigue in the fog owing to the low coelicient of diffusionof the light radiation through the fog, smoke and the like and/or a bluelter to obtain concealment of mechanised troop transe ports and preventdiiusion of light through particular atmospheric fog accumulations,fumous walls or gas fogs. The latter filter may also be combined withthe yellow filter and in certain conditions it may improve visibility.

According to the construction shown in Fig. 3 a parabolic reflector lais used in combination with a lens I2 to concentrate the rays issuingfrom the focus F onto the focus F.

The invention comprises further a particular form of the lens 1, whichmay be, as shown in Fig. 1, constituted by a front convex portion and arear conical portion in order to reduce the focal distance. In lieu ofthe lens shown in Fig. 1 a. two-focal lens may be advantageously used inorder to correct aberrations. For this purpose a lens constituted by twoparts I and 1 may be used, as shown in Fig. 4.

What I claim is:

Lamp for vehicle comprising in combination a reflector constituted by anellipsoidal rear portion and a cylindrical front portion, a source oflight supstantially in a focus of said ellipscidal portion so as toconcentrate the light beam in a caustic in the other focus, a cover in avertical plane extending through the last-mentioned focus and having acentral opening, a blade adjacent said caustic adjustably mounted onsaid cover, a second blade located above said caustic pivoted at one endto the cover and provided at its other end with a remote control, an armcarrying a colored filter rotatably mounted on said cover adjacent saidsecond-mentioned upper blade, means for bringing at will said coloredfilter into said caustic, a tubular body applied to the cover about saidopening and having its inner surface blackened, and a conical-convexemergence lens at the end of said tubular body.

AROLDO CHITI.

